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Automatic extraction of road features from LiDAR data is a fundamental task for different applications, including asset management. The availability of updated and reliable models is even more important in the context of smart roads. One of the main advantages of LiDAR data compared with other sensing instruments is the possibility to directly get 3D information. However, the task of deriving road networks form LiDAR data acquired with Airborne Laser Scanning (ALS) may be quite complex due to occlusions, low feature separability and shadowing from contextual objects. Indeed, even if roads elements can be identified in the ALS point cloud, the automated identification of the network starting form them can be involved due to large variability in the size of roads, shapes and presence of connected off-road features such as parking lots. This paper presents a workflow aimed at partially solving the automatic creation of a road network from high-resolution ALS data. The presented method consists of three main steps: (i) labelling of road points; (ii) a multi-level voting scheme; and (iii) the regularization of the extracted road segments. The developed method has been tested using the “Vaihingen”, “Toronto” and “Tobermory” data set provided by the ISPRS.

In the wake of the success of Deep Learning Networks (DLN) for image recognition, object detection, shape classification and semantic segmentation, this approach has proven to be both a major breakthrough and an excellent tool in point cloud classification. However, understanding how different types of DLN achieve still lacks. In several studies the output of segmentation/classification process is compared against benchmarks, but the network is treated as a “black-box” and intermediate steps are not deeply analysed. Specifically, here the following questions are discussed: (1) what exactly did DLN learn from a point cloud? (2) On the basis of what information do DLN make decisions? To conduct such a quantitative investigation of these DLN applied to point clouds, this paper investigates the visual interpretability for the decision-making process. Firstly, we introduce a reconstruction network able to reconstruct and visualise the learned features, in order to face with question (1). Then, we propose 3DCAM to indicate the discriminative point cloud regions used by these networks to identify that category, thus dealing with question (2). Through answering the above two questions, the paper would like to offer some initial solutions to better understand the application of DLN to point clouds.

Growing interest in boosting urban identity and character is increasing the demand for historic maps and documents of cities in constant evolution as in the case of metropolitan areas, peripheries and riverbank sites. A ‘Heritage & Development strategy based on the Historic Urban Landscape approach is required by city makers to ensure that exploitation needs can valorise the site’s natural and cultural heritage for sustainable social and economic optimisation.This paper intends to propose innovative virtual hub technologies of brokering, discovering and accessing open data, making available - to a large public of users - the multi-temporal dense stratified evidences of the targeted built environment areas and its surroundings, through the navigation of geo-referenced historical maps, together with current maps, going through design data. Enhancing the practice of publishing maps as open data represents a powerful leverage for time and cost effectiveness among planners, scientists and historians; soliciting their use to gain a vast knowledge of that areas, including a better comprehension of the transformations over the centuries, in order to support decision-making analysis, environmental monitoring and urban area planning; thus contribute to improving the sustainability of interventions respectful of the identity of the urban landscape. A case study of the ‘Deux Rives’ planning area in the city of Strasbourg is presented to illustrate these issues. The City of Strasbourg’s commendable work in publishing the historical maps supports the municipal authority’s Heritage & Development strategy in meeting contemporary and future needs while mitigating long-term damage from pressures for new interventions. Innovative virtual hub based applications to gather open data coming from different sources (city territorial services, design data sources, mobility services) can result in immeasurable added value through communicating the wealth of the planned areas and raising awareness among citizens and visitors of the interventions.

This paper presents the survey of the Baptistery of the Collegiata Museum (Castiglione Olona - Italy), painted by Masolino da Panicale in 1435. Surveying activity was carries out throughout the use of combined digital techniques of documentation (topographic measurements, laser scanning, digital photogrammetry, thermal imaging, digital photography). Different data were collected inside and outside the Baptistery following a multi-resolution reconstruction that ranges from the whole Baptistery up to small details. Laser scans were also used to obtain a digital representation of inner volumes of the structure. Registered scans were uploaded into a modelling software, in order to produce a 3D model based on scan data, increasing the correspondence with the existent building; this model can be used to better understand the volume arrangement, also for educational and dissemination purposes. A particular attention was devoted to documentation of graffiti scratched onto the frescos, since their presence is a significative evidence of the history of the building. A digital-based workflow was set out in order to assure high quality outputs in respect of the conservation needs.This multi-resolution approach proved to be a suitable solution when dealing with features, such as ancient architectures, with a high number of complex details to be correctly recorded and joint together as starting point and support of historical researches. Results and scope are here presented.

Informative models are not limited only to new construction or existing building but can also be used (also been used) for large infrastructure management like bridges. The adoption of informative content models for structural health monitoring (SHM) of such infrastructures poses some issues that need to be solved in order to develop smooth management and maintenance workflows. This paper describes a novel methodology for the generation of a detailed BIM of a complex medieval bridge and the possibility to link specific data coming from load testing. Integration of information coming from different data sources is one of the most important aspects for the development of maintenance programs. However, each actor in the process makes use of different strategies and protocols whose integration can generate bottlenecks. To partially overcome this limitation a cloud-based solution was used, and a Building Information Model (BIM) of the bridge was used as main collector of information for the different stakeholders involved in its management.

The development of advanced survey techniques in the last years is offering a wide set of tools for implementing the building analysis. In the preservation field, the use of 3D interactive models is a prerogative of few and rare excellent cases and the information contained in high-resolution virtual representation are only partially developed. In the past centuries, the representation was centred on the theoretical roles of the descriptive geometry devoted to the representation of the architectural elements complexity in the space to manage the construction site process. It has been progressively lost the past skill to managing 3D objects in the space. Being HBIM based on 3D solids representation, the theme of the 3D model comes back to the foreground. The complexity of the architectural heritage and its components is evidencing a gap of best practices, protocols and specification in the HBIM-modeling. Do-It-Yourself modeling process has been characterised by the first phase of HBIM generation in the last years. Modeling phase within HBIM is left to the single responsibility, with lack of specification on the accuracy and level of geometry.This paper presents a first tentative to summarize the relationship among the surveying accuracy, the Level of Geometry and the Level of Accuracy (LOA) of each BIM object, starting from a series of experiences, in which advanced survey techniques were applied to condition assessment required by architectural preservation HBIM approach. The objectives of the surveying and HBIM can change for different aspects: but in the preservation context the specificity of each single objects and their complexity need to be taken into account. As in the surveying, the choice of a scale implies a range of accuracy and tolerance in the data acquisition and processing, in HBIM modelling the choice of the Grade of Accuracy drives within the Level of Geometry the scale model that is expected to be performed and required by the different actors involved by the different phases (i.e. restoration, Energy Efficiency, Finite Element Analysis, CoSiM). On the base of different experiences occurred in the last years, the specifications conventionally adopted for the surveying have been here proposed and extended to the HBIM domain, particularly in the modelling of objects, in order to classify different accuracies. A transparent choice of accuracy allows to define the LOG and to support the adoption of the proper Grade of Generation among the different options (GOG1-10) in function of the point clouds geometry and of the scales chosen by the different actors. The architectural scale together with the urban scale (Heritage Urban Level) is considered as well to keep advantage of a multi-resolution model, diversified in function of the objectives, thus of Level of accuracy (and Level of Information) and Level of Geometry.

The protection and management of archaeological sites require from a deep documentation and analysis, and although hand measuring and documentation is the cheapest way for collecting data, laser scanner has been gradually integrated for the geometrical data capture since point clouds have a high quality in terms of accuracy, precision and resolution. Although acquisition with laser scanner is considered a quick process, scan planning is of high relevance when considering outdoor archaeological sites because of their large size and complexity. In this paper, an automatic methodology to optimize the number and position of scans in order to obtain a point cloud of high quality in terms of data completeness is proposed. The aim of the methodology is to minimize the number of scans, minimizing at the same time the estimated surveying time and the amount of repetitive acquired data. Scan candidates are generated by using a grid-based and a triangulation-based distribution, and results show a faster analysis when triangulation is implemented. The methodology is tested into two real case studies from Italy and Spain, showing the applicability of scan planning in archaeological sites Xunta de Galicia | Ref. ED481B 2016/079-0 Xunta de Galicia | Ref. ED431C 2016-038 Universidade de Vigo | Ref. 00VI 131H 641.02 Ministerio de Economía, Industria y Competitividad | Ref. TIN2016-77158-C4-2-R Ministerio de Economía, Industria y Competitividad | Ref. RTC-2016-5257-7 European Cooperation in Science and Technology (COST) | Ref. CA15201

Ancient graffiti are a valuable and constant historical evidence through the human history, regardless from the geographic area or historical period. They can be found on different kinds of surfaces and in different contexts, such as religious building or civic structures, in public or private environments. Their study and comprehension need to be grounded on good and complete documentation techniques. The application of accurate recording methods is even more important for ancient graffiti, for a series of reasons. First of all, their perception is often less immediate than other historical or artistic evidence, and directly depends on external aspects, such as the lighting conditions, and personal skills. Moreover, their interpretation is often challenging also for expert scholars, so as to require both the most objective reproduction possible and the personal interpretation of the scholar. As a case study, several late medieval graffiti scratched on frescos have been documented with digital methods. Results will be presented and discussed. This paper will mainly focus on graffiti scratched on frescos or plaster, and not on petroglyphs, i.e. marks and drawings on rock surfaces.

In recent years, many efforts have been invested in the cultural heritage digitization: surveying, modelling, diagnostic analysis and historic data collection. Nowadays, this effort is finalized in many cases towards historical building information modelling (HBIM). However, the architecture, engineering, construction and facility management (AEC-FM) domain is very fragmented and many experts operating with different data types and models are involved in HBIM projects. This prevents effective communication and sharing of the results not only among different professionals but also among different projects. Semantic web tools may significantly contribute in facilitating sharing, connection and integration of data provided in different domains and projects. The paper describes this aspect specifically focusing on managing the information and models acquired on the case of vaulted systems. Information is collected within a semantic based hub platform to perform cross correlation. Such functionality allows the reconstructing of the rich history of the construction techniques and skilled workers across Europe. To this purpose an ontology-based vaults database has been undertaken and an example of its implementation is presented. The developed ontology-based vaults database is a database that makes uses of a set of ontologies to effectively combine data and information from multiple heterogeneous sources. The defined ontologies provide a high-level schema of a data source and provides a vocabulary for user queries.

Virtual Museums (VMs) have emerged from the ongoing crossbreeding process between museums and digital technologies as an additional "channel" for disseminating content and providing knowledge about cultural heritage. VMs is a concept still in definition, as this paper attempts to briefly retrace, the recognition of its potential has motivated our efforts for further developments. Core questions that motivated the first phase of the research presented have been: can digital storytelling become the key feature of future VMs? May narratives approach support communication and understanding of cultural heritage providing enriching encounters with the past? May complex systems, such as the built environment and landscape (characterized by space-time relations among elements, that are often difficult to read or appreciate) find in digital storytelling a method that exploits their values as documents and palimpsests of human history? Can an increased awareness of the past contribute to support a sense of belonging and identity construction? Which kind of stories can be currently designed with the existing tools? The paper, after an introductory overview, provides a tentative reply to these questions combining the main findings offered by a series of recent studies related to this scenario with some preliminary direct investigations and, eventually, it proposes some outlooks for future developments.

Fisheye lenses are becoming more popular in complete image-based modelling projects of small and narrow spaces. The growing interest in fisheye lenses is confirmed by the availability of different commercial software incorporating a fisheye camera model. Such software are now able to carry out the steps of the image processing pipeline in a fully automated way, from camera calibration and orientation to dense matching, surface generation, and orthophoto production. This paper highlights the advantages (and disadvantages) of fisheye lenses when used for 3D modelling projects through different commercial software. The goal is not only a comparison of commercial software, but also an analysis of the additional issues that arise when a fisheye lens is used for 3D modelling. Results confirm that a fisheye lens is suitable for accurate metric documentation, especially when limited space is available. On the other hand, additional issues where found during the camera calibration/image orientation step as well as the texture generation and orthophoto production phases, for which particular attention is required.

The article focuses on the analysis of the construction technique of the star vault designed by the famous Bohemian architect from the Baroque period, Jan Blažej Santini-Aichel. The vault covers St. Bernard’s Chapel in the Plasy Monastery and represents a masterpiece in Santini’s late career. The authors try to understand its construction technology with the help of modern surveying methods. The shape of the vault structure is complex, therefore a detailed geometrical survey of both intrados and extrados was performed. The data collected in situ, photogrammetric blocks, were used as a basis for the modeling of the vault shape. An accurate 3D model and HBIM of the structure were generated, using a novel Scan-to-BIM process based on the integrated use of a different Grade of Generation and primitive extraction to support the modeling. This survey is part of a program to implement a vault database addressed to detect permanencies and mutations in the construction techniques across Europe, that gives back unexpected, and mostly unknown, richness of vault construction patterns.

This paper presents a strategy to measure verticality deviations (i.e. inclination) of tall chimneys. The method uses laser scanning point clouds acquired around the chimney to estimate vertical deviations with millimeter-level precision. Horizontal slices derived from the point cloud allows us to inspect the geometry of the chimney at different heights. Two methods able to estimate the center at different levels are illustrated and discussed. A first solution is a manual approach that uses traditional CAD software, in which circle fitting is manually carried out through point cloud slices. The second method is instead automatic and provides not only center coordinates, but also statistics to evaluate metric quality. Two case studies are used to explain the procedures for the digital survey and the measurement of vertical deviations: the chimney in the old slaughterhouse of Piacenza (Italy), and the chimney in Leonardo Campus at Politecnico di Milano (Italy).

In the last years many efforts have been invested in the cultural heritage digitization: surveying, modelling, diagnostic analysis and historic data collection. Nowadays, this effort is finalized in many cases towards the Historical Building Information Modelling. The number of informative models testifying the multifaceted richness and unicity of the architectural heritage and its components is progressively increasing. Information and Model are generally acquired under researches and analysis phases addressed to the preservation and restoration process. Unfortunately, once concluded the research such documentation is mostly left abandoned in the drawers or in the local memory of the computers, and in some cases totally missed. Just a few of them are saved in a server or in the cloud for the duration of the restoration, but without any connection with the maintenance process of historic architectures or knowledge transfer purposes and dissemination. This data loss would lead to the breaking of the cycle of past, present and future, with loss of memory and knowledge. The paper start facing the aspect of managing the information and models acquired on the case of vaulted systems. Information is collected within a semantic based hub platform to perform cross co-relation at a PanEuropean level. Such functionality allows to reconstruct the rich history of the construction techniques and skilled workers across Europe, enriched by 3 case studies surveyed in Prague region. To this purpose a Vault DB has been undertaken with a Vocabulary enriched by the granular information gained from the HBIM models, and with the vault sub-typologies highlighted by a detailed surveying.

The use of rational functions has become a standard for very high-resolution satellite imagery (VHRSI). On the other hand, the overall geolocalization accuracy via direct georeferencing from on board navigation components is much worse than image ground sampling distance (predicted < 3.5 m CE90 for WorldView-3, whereas GSD = 0.31 m for panchromatic images at nadir). This paper presents the georeferencing accuracy results obtained from a single WorldView-3 image processed with a bias compensated RPC camera model. Orientation results for an image collected over Milan are illustrated and discussed for both direct and indirect georeferencing strategies as well as different bias correction parameters estimated from a set of ground control points. Results highlight that the use of a correction based on two shift parameters is optimal for the considered dataset.

Building Information Modelling is not limited to buildings. BIM technology includes civil infrastructures such as roads, dams, bridges, communications networks, water and wastewater networks and tunnels. This paper describes a novel methodology for the generation of a detailed BIM of a complex medieval bridge. The use of laser scans and images coupled with the development of algorithms able to handle irregular shapes allowed the creation of advanced parametric objects, which were assembled to obtain an accurate BIM. The lack of existing object libraries required the development of specific families for the different structural elements of the bridge. Finally, some applications aimed at assessing the stability and safety of the bridge are illustrated and discussed. The BIM of the bridge can incorporate this information towards a new “BIMonitoring” concept to preserve the geometric complexity provided by point clouds, obtaining a detailed BIM with object relationships and attributes.

Geospatial data are today more and more widespread. Many different institutions, such as Geographical Institutes, Public Administrations, collaborative communities (e.g., OSM) and web companies, make available nowadays a large number of maps. Besides this cartography, projects of digitizing, georeferencing and web publication of historical maps have increasingly spread in the recent years. In spite of these variety and availability of data, information overload makes difficult their discovery and management: without knowing the specific repository where the data are stored, it is difficult to find the information required and problems of interconnection between different data sources and their restricted interoperability limit a wide utilization of available geo-data. This paper aims to describe some actions performed to assure interoperability between data, in particular spatial and geographic data, gathered from different data providers, with different features and referring to different historical periods. The article summarizes and exemplifies how, starting from projects of historical map digitizing and Historical GIS implementation, respectively for the Lombardy and for the city of Parma, the interoperability is possible in the framework of the ENERGIC OD project. The European project ENERGIC OD, thanks to a specific component – the virtual hub – based on a brokering framework, copes with the previous listed problems and allows the interoperability between different data sources.

The latest information technology developments in the field of digital heritage (DH) have enabled the creation of novel virtual experiences favouring information-sharing connected to the 3D digital reconstruction of historical and existing buildings. In recent years, Building Information Modelling for historic buildings (HBIM) projects are the most applied methods to transmit the richness of built heritage from both the geometrical and informative points of view, but they are not always adequate to ensure a simple reading of different type of information for not-expert users. For this reason, further investigations were performed, following a novel SCAN-to-BIM process based on novel Grades of Generation (GOG 9 and 10) in order to digitally represent one of the most complex structure of the Basilica of Sant’Ambrogio in Milan. It is composed of arches supported by pillars, characterised by a double-wave curve, both on its vertical and horizontal axis. The information coming from the previous studies, such as historical documentation, as-found drawings, building archaeology analysis (materials and brick surface texture) and decay data (crack patterns, material discontinuity), was integrated with a novel webimmersive solution able to display 360° pictures, video and HBIM simultaneously. A detailed comparison of the 360 multimedia data of the current arrangement with the one of the HBIM historical phases allow experts and not-experts to analyse the transformation of the arch structures in a new immersive environment with different devices such as laptops, mobile phones and latest virtual and augmented reality (VR-AR) headset.

A critical task in every terrestrial laser scanning project is the transformation (addressed to as registration or alignment) of multiple point clouds into a common reference system. Even though this operation appears to be a solved and well-understood problem, the vast majority of available techniques still lack meaningful quality measures that allow the user to understand and analyze the final outputs. The erroneous estimation of registration parameters may cause systematic biases that falsify those subsequently outcomes such as deformation measurements on historical buildings, CAD-drawings of individual elements, or 3D models devoted to analyze the verticality of a tower. Thus, this article compares three common registration algorithms, namely target-based registration, the Iterative-Closest Point algorithm (ICP) as well as a plane-based approach on examples related to different case studies concerning historical buildings.

Metric documentation of buildings requires the connection of different spaces, such as rooms, corridors, floors, and interior and exterior spaces. Images and laser scans have to be oriented and registered to obtain accurate metric data about different areas and the related metric information (e.g., wall thickness). A robust registration can be obtained with total station measurements, especially when a geodetic network with multiple intersections on different station points is available. In the case of a photogrammetric project with several images acquired with a central perspective camera, the lack of total station measurements (i.e., control and check points) could result in a weak orientation for the limited overlap between images acquired through doors and windows. The procedure presented in this paper is based on 360° images acquired with an affordable digital camera (less than 350$). The large field of view of 360° images allows one to simultaneously capture different rooms as well as indoor and outdoor spaces, which will be visible in just a picture. This could provide a more robust orientation of multiple images acquired through narrow spaces. A combined bundle block adjustment that integrates central perspective and spherical images is here proposed and discussed. Additional considerations on the integration of fisheye images are discussed as well.

Nowadays, the digital reconstruction of vaults is carried out using photogrammetric and laser scanning techniques able to capture the visible surface with dense point clouds. Then, different modeling strategies allow the generation of 3D models in various formats, such as meshes that interpolates the acquired point cloud, NURBS-based reconstructions based on manual, semi-automated, or automated procedures, and parametric objects for Building Information Modeling. This paper proposes a novel method that reconstructs the visible surface of a vault using neural networks. It is based on the assumption that vaults are not irregular free-form objects, but they can be reconstructed by mathematical functions calculated from the acquired point clouds. The proposed approach uses the point cloud to train a neural network that approximates vault surface. The achieved solution is not only able to consider the basic geometry of the vault, but also its irregularities that cannot be neglected in the case of accurate and detailed modeling projects of historical vaults. Considerations on the approximation capabilities of neural networks are illustrated and discussed along with the advantages of creating a mathematical representation encapsulated into a function.

This paper will go into further detail on pressures and policies faced by the archaeological site of San Clemente’s caretakers, that affect the sites preservation. Including the protection of the riverbed along the fragile coast line represented by the masonry portion of the thermal bath’s foundation which is directly in contact with the water. Being the destiny of the site to be gradually eroded by flooding, digital documentation can play a significant role in documenting the sites changes over time allowing for easy analysis of newly revealed elements. As in the case of the documentation of the viewable openings through the thermal masonry-pipeline during the last surveying campaign this paper will discuss the experimentation of data management through Virtual Hub. Through which past sequences of data can be made accessible to anyone who must operate on the site, and to document the state of affairs of the archaeological complex over the last few years.

Many European infrastructures dating back to '50 and '60 of the last century like bridges and viaducts are approaching the end of their design lifetime. In most European countries costs related to maintenance of infrastructures reach a quite high percentage of the construction budget and additional costs in terms of traffic delay are due to downtime related to the inspection and maintenance interventions. In the last 30 years, the rate of deterioration of these infrastructures has increased due to increased traffic loads, climate change related events and man-made hazards. A sustainable approach to infrastructures management over their lifecycle plays a key role in reducing the impact of mobility on safety (over 50 000 fatalities in EU per year) and the impact of greenhouse gases emission related to fossil fuels. The events related to the recent collapse of the Morandi bridge in Italy tragically highlighted the sheer need to improve resilience of aging transport infrastructures, in order to increase the safety for people and goods and to reduce losses of functionality and the related consequences. In this focus Structural Health Monitoring (SHM) is one of the key strategies with a great potential to provide a new approach to performance assessment and maintenance over the life cycle for an efficient, safe, resilient and sustainable management of the infrastructures. In this paper research efforts, needs and challenges in terms of performance monitoring, assessment and standardization are described and discussed., The networking support of COST Action TU1402 on ‘Quantifying the Value of Structural Health Monitoring’ and of COST Action TU1406 on ‘Quality specifications for roadway bridges, standardization at a European level (BridgeSpec)’

HBIM (Heritage Building Information Modelling) can be nowadays considered as part of the digitization process of Cultural Heritage, with the particular characteristics that being born to manage Models and Data within a unique environment they can be inherited to adopt a synergic approach to the cultural Heritage ‘as a whole system’. To this aim they need to overcome gaps and barriers undertaking an holistic approach in many directions. The paper intends to introduce an overview on the meaning of Holistic Heritage Information Building. The attribute holistic is here used with the meaning to empower instruments and methods capable to interconnect single HBIM nodes within networks where to find the information collected in a cross sectorial space: vocabularies, libraries of object and semantics, derived from such ‘Informative Models’ - with the support of Virtual Hub technologies - can boost nodes-networking empowering the capabilities of BIM Informative Modelling together with web accessible Geographic Informative System. Such richness once interconnected can be accessed from space-temporal queries, semantic searches, and harvested with other networks in order to enhance the cross correlation of the information and allowing the sharing of different case studies and HBIM within a space-temporal framework. This will allow the comparison of masonry texture, history of material finishing and skilled workers across space and time. HHBIM HUBS will be a gate toward the eXtended Reality potentials attracting and distributing data coming from different sources.

Mensiochronology of brickwork, even in areas where reference curves have been constructed and well tested, requires precise measurements and a representative amount of data due to the many factors affecting the reliability of the measurements, such as the defects caused by the time and the environment that changed the geometry of the bricks (deformation or lack of material along the edges), as well as the operators’ skills. Sometimes, the number of measurable bricks is limited in a wall, or in a stratigraphic unit. Furthermore, if a scaffolding is not available, the analysis is concentrated only on the lower courses of the bricks, being not possible to directly measure the bricks of the higher levels. In order to implement the number of bricks taken into account for this study, a comparison from direct measurements and indirect measurements is here proposed.The aim of this paper is to explore the applications of photogrammetry for undertaking brick measurements for chronological dating: its advantage and drawbacks. Using high-resolution digital rectified pictures, the masonry texture of some well-documented building prospects was scaled into vector graphic software for recording the measures of the bricks. The results presented here by the authors are an attempt for validating this method for future applications. In detail, three case studies are analysed in the historic centre of Vimercate (Italy) testing the effectiveness of the presented method on dated buildings that display diverse features, including the presence of reused bricks, possibly coming from dismantled pre-existing structures. The results proved that the proposed geomatics method entails an accuracy that does not affect the usability of data for the investigation of buildings and the material culture inbuilt.

Automated identification of high-level structures in unorganized point cloud of indoor spaces Indoor space is an important aspect of scene analysis that provides essential information for many applications, such as building digitization, indoor navigation and evacuation route planning. In addition, detection of repetition and regularities in the organization indoor environments, such as rooms, can be used to provide a contextual relationship in the reconstruction phase. However, retrieving high-level information is a challenging task due to the unorganized nature of the raw data, poor-quality of the input data that are in many cases contaminated with noise and outliers. in point benefit from the apparent regularities and strong contextual relationships in façades. The main observation exploited in this paper is the fact that building indoor is generally constituted by a set of basic shapes repeated several times in regular layouts. Building elements can be considered as similar if they share a set of features and elements in an idealized layout exhibiting some regularities. Starting from this main assumption a recursive adaptive partitioning of the indoor point cloud is carried out to automatically derive a flexible and hierarchical 3D representation of the building space. The presented methodology is tested on a synthetic dataset with Gaussian noise. The reconstructed pattern shows a close correspondence with the synthetic one showing the viability of the proposed approach.

In the last years, point clouds have become the main source of information for building modelling. Although a considerable amount of methodologies addressing the automated generation of 3D models from point clouds have been developed, indoor modelling is still a challenging task due to complex building layouts and the high presence of severe clutters and occlusions. Most of methodologies are highly dependent on data quality, often producing irregular and non-consistent models. Although manmade environments generally exhibit some regularities, they are not commonly considered. This paper presents an optimization-based approach for detecting regularities (i.e., same shape, same alignment and same spacing) in building indoor features. The methodology starts from the detection of openings based on a voxel-based visibility analysis to distinguish ‘occluded’ from ‘empty’ regions in wall surfaces. The extraction of regular patterns in windows is addressed from studying the point cloud from an outdoor perspective. The layout is regularized by minimizing deformations while respecting the detected constraints. The methodology applies for elements placed in the same plane.

Despite the increasing demand of updated and detailed indoor models, indoor reconstruction from point clouds is still in an early stage in comparison with the reconstruction of outdoor scenes. Specific challenges are related to the complex building layouts and the high presence of elements such as pieces of furniture causing clutter and occlusions. This work proposes an automatic method for modelling Manhattan-World indoors acquired with a mobile laser scanner in the presence of highly occluded walls. The core of the methodology is the transformation of indoor reconstruction into a labelling problem of structural cells in a 2D floor plan. Assuming the prevalence of orthogonal intersections between walls, indoor completion is formulated as an energy minimization problem using graph cuts. Doors and windows are detected from occlusions by implementing a ray-tracing algorithm. The methodology is tested in a real case study. Except for one window partially covered by a curtain, all building elements were successfully reconstructed.

360 degree cameras capture the whole scene around a photographer in a single shot. Cheap 360 cameras are a new paradigm in photogrammetry. The camera can be pointed to any direction, and the large field of view reduces the number of photographs. This paper aims to show that accurate metric reconstructions can be achieved with affordable sensors (less than 300 euro). The camera used in this work is the Xiaomi Mijia Mi Sphere 360, which has a cost of about 300 USD (January 2018). Experiments demonstrate that millimeter-level accuracy can be obtained during the image orientation and surface reconstruction steps, in which the solution from 360° images was compared to check points measured with a total station and laser scanning point clouds. The paper will summarize some practical rules for image acquisition as well as the importance of ground control points to remove possible deformations of the network during bundle adjustment, especially for long sequences with unfavorable geometry. The generation of orthophotos from images having a 360° field of view (that captures the entire scene around the camera) is discussed. Finally, the paper illustrates some case studies where the use of a 360° camera could be a better choice than a project based on central perspective cameras. Basically, 360° cameras become very useful in the survey of long and narrow spaces, as well as interior areas like small rooms.

The aim of this work is to study the value and potential of UAV technology as an instrument for documenting and analyzing a heritage site on both the detailed scale and the wider territorial scale. In particular, this paper will focus on the application of an UAV platform on the archeological site of Isola Comacina (Comacina Island), in the Lago di Como (Lake Como, Lombardy, Northern Italy). The work considers the advantages of different metric scales and the use of both RGB and thermal imagery, along with other terrestrial data (total station measurements and laser scans), in order to arrive at a working heritage information model. In particular, the archaeological remains on Isola Comacina have been intensively studied before by standard techniques but unfortunately no wider context is provided. A part of the research is the investigation of new methodologies offered by accurate geometric reconstructions combined with thermal imagery acquired by means of UAV platforms, e.g. the support of this type of imagery to discover rock formations partially buried.

Documentation on archaeological fieldworks needs to be accurate and time-effective. Many features unveiled during excavations can be recorded just once, since the archaeological workflow physically removes most of the stratigraphic elements. Some of them have peculiar characteristics which make them hardly recognizable as objects and prevent a full 3D documentation. The paper presents a suitable feature-based method to carry on archaeological documentation with a three-dimensional approach, tested on the archaeological site of S. Calocero in Albenga (Italy). The method is based on one hand on the use of structure from motion techniques for on-site recording and 3D Modelling to represent the three-dimensional complexity of stratigraphy. The entire documentation workflow is carried out through digital tools, assuring better accuracy and interoperability. Outputs can be used in GIS to perform spatial analysis; moreover, a more effective dissemination of fieldworks results can be assured with the spreading of datasets and other information through web-services.

In this paper we present an automated method to derive highly detailed 3D vector models of modern building façades from terrestrial laser scanning data. The developed procedure can be divided into two main steps: firstly the main elements constituting the façade are identified by means of a segmentation process, then the 3D vector model is generated including some priors on architectural scenes. The identification of main façade elements is based on random sampling and detection of planar elements including topology information in the process to reduce under- and over-segmentation problems. Finally, the prevalence of straight lines and orthogonal intersections in the vector model generation phase is exploited to set additional constraints to enforce automated modeling. Contemporary a further classification is performed, enriching the data with semantics by means of a classification tree. The main application field for these vector models is the design of external insulation thermal retrofit. In particular, in this paper we present a possible application for energy efficiency evaluation of buildings by mean of Infrared Thermography data overlaid to the façade model.

In December 2012 ENIservizi (the Italian multi-national energy agency operating in many countries), after the Earthquake that occurred in April 2009, decided to undertake the project ‘Re-start from Collemaggio’ with the aim of giving new hope to the L’Aquila community, funding around 14 million Euro to restore the Basilica di Collemaggio. The Superintendence Office carried on the restoration project with the scientific support of the Università degli Studi de L’Aquila and the Università La Sapienza di Roma, under the coordination of the Politecnico di Milano. ENIservizi, aware of the BIM potential in the complex building and infrastructure domain in the world, required an advanced HBIM from the laser scanner and photogrammetric surveying to support the diagnostic analysis, the design project, the tender and the restoration itself, today still on course. Plans and vertical sections were delivered (2012) starting from the surveying campaigns (February and June 2013), together with the first HBIM advancement from the end of 2012 in support of the preliminary-definitive-executive steps of the restoration design project (2013-14-15). Five years later, this paper tries to make a synthesis of the different lessons learnt, in addition to the positive and critical aspects relating HBIM feasibility, sustainability and usefulness to the challenging restoration work. In particular, the Collemaggio BIM experience anticipated the new Italian Public Procurement Legislation (D.Lgs 50/2016, Nuovo Codice degli Appalti pubblici) aligned with to the EUPPD 24/2014: the EU Directive on Public Procurement asked all the 28 EU countries to adopt building informative modelling by February 2016 in order to support the whole LCM (Life Cycle Management), starting from the project and the intervention, through rewarding scores or mandatory regulations. Many analyses foresees to save from around 5% to 15% of the overall investment by adopting mature BIM (Level 3 to 5), particularly 4D remotely controlled BIM in support of the LCM, as in the case of maintenance and management process. The tender for Basilica restoration was published in 2015: the process was not developed enough to introduce selective criteria based on BIM adoption by the Construction Industry due to the lack of legislation at that time and the lack of BIM skills among the companies. Nevertheless ENIservizi also separately funded aside the HBIM of the Basilica to tackle an advanced BIM able to address decision-making processes in the heritage domain among the different actors: to support operators, architects, structural engineers, economic computation, construction site management and restoration, the theoretical and practical approach adopted by the HBIM, overcame the current logic based on sequential LoD (from simplex to complex, from the preliminary to the executive design) that is typical of new constructions in favour of a complex LoD approach that could guarantee management of the richness, unicity and multiplicity of each component and the maximum degree of knowledge in order to derive the decisions from the starting phases of the project. On the lesson learnt from this experience, the process of updating the current codification criteria (UNI11337-2009) was started with a draft proposal stimulating a debate for the future of HBIM adoption.

Recent developments in Building Information Modelling (BIM) technologies are facilitating the management of historic complex structures using new applications. This paper proposes a generative method combining the morphological and typological aspects of the historic buildings (H-BIM), with a set of monitoring information. This combination of 3D digital survey, parametric modelling and monitoring datasets allows for the development of a system for archiving and visualizing structural health monitoring (SHM) data (Fig. 1). The availability of a BIM database allows one to integrate a different kind of data stored in different ways (e.g. reports, tables, graphs, etc.) with a representation directly connected to the 3D model of the structure with appropriate levels of detail (LoD). Data can be interactively accessed by selecting specific objects of the BIM, i.e. connecting the 3D position of the sensors installed with additional digital documentation. Such innovative BIM objects, which form a new BIM family for SHM, can be then reused in other projects, facilitating data archiving and exploitation of data acquired and processed. The application of advanced modeling techniques allows for the reduction of time and costs of the generation process, and support cooperation between different disciplines using a central workspace. However, it also reveals new challenges for parametric software and exchange formats. The case study presented is the medieval bridge Azzone Visconti in Lecco (Italy), in which multi-temporal vertical movements during load testing were integrated into H-BIM.

The Samsung Gear 360 is a consumer grade spherical camera able to capture photos and videos. The aim of this work is to test the metric accuracy and the level of detail achievable with the Samsung Gear 360 coupled with digital modelling techniques based on photogrammetry/computer vision algorithms. Results demonstrate that the direct use of the projection generated inside the mobile phone or with Gear 360 Action Direction (the desktop software for post-processing) have a relatively low metric accuracy. As results were in contrast with the accuracy achieved by using the original fisheye images (front and rear facing images) in photogrammetric reconstructions, an alternative solution to generate the equirectangular projections was developed. A calibration aimed at understanding the intrinsic parameters of the two lenses camera, as well as their relative orientation, allowed one to generate new equirectangular projections from which a significant improvement of geometric accuracy has been achieved.

This paper describes the use of BIM models derived from point clouds for structural simulation based on Finite Element Analysis (FEA). Although BIM interoperability has reached a significant level of maturity, the density of laser point clouds provides very detailed BIM models that cannot directly be used in FEA software. The rationalization of the BIM towards a new finite element model is not a simple reduction of the number of nodes. The interconnections between the different elements and their materials require a particular attention: BIM technology includes geometrical aspects and structural considerations that allow one to understand and replicate the constructive elements and their mutual interaction. The information must be accurately investigated to obtain a finite element model suitable for a complete and detailed structural analysis. The aim of this paper is to prove that a drastic reduction of the quality of the BIM model is not necessary. Geometric data encapsulated into dense point clouds can be taken into consideration also for finite element analysis.

Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelling of indoor/outdoor urban environments. In the case of large structures, multiple scans may be required to cover the entire scene and registration is needed to merge them together. In general, the identification of corresponding geometric features among a series of scans can be used to compute the 3D rigid-body transformation useful for the registration of each scan into the reference system of the final point cloud. Different automatic or semi-automatic methods have been developed to this purpose. Several solutions based on artificial targets are available, which however may not be suitable in any situations. Methods based on surface matching (like ICP and LS3D) can be applied if the scans to align have a proper geometry and surface texture. In the case of urban and architectural scenes that present the prevalence of a few basic geometric shapes ("Legoland" scenes) the availability of many planar features is exploited here for registration. The presented technique does not require artificial targets to be added to the scanned scene. In addition, unlike other surface-based techniques (like ICP) the planar feature-based registration technique is not limited to work in a pairwise manner but it can handle the simultaneous alignment of multiple scans. Finally, some applications are presented and discussed to show how this technique can achieve accuracy comparable to a consolidated registration method.

The paper presents a strategy able to derive and process high resolution images created by means of gnomonic projections. The implemented pipeline can be split into two phases: first, the sensor resolution of the camera is physically increased by acquiring and merging a set of images with a rotating camera equipped with a long focal lens; then the new set of gnomonic projections is processed with a 3D reconstruction methodology able to deal with very large images. Several issues are addressed in the paper, starting from image acquisition up to 3D modelling. Gnomonic projections have been demonstrated to be powerful tools when traditional pinhole images do not allow the reconstruction of small and fine details. Examples and comparisons aimed at determining the correctness of the mathematical approach for image orientation are illustrated as well.

This paper presents a photogrammetric methodology for true-orthophoto generation with images acquired from UAV platforms. The method is an automated multistep workflow made up of three main parts: (i) image orientation through feature-based matching and collinearity equations / bundle block adjustment, (ii) dense matching with correlation techniques able to manage multiple images, and true-orthophoto mapping for 3D model texturing. It allows automated data processing of sparse blocks of convergent images in order to obtain a final true-orthophoto where problems such as self-occlusions, ghost effects, and multiple texture assignments are taken into consideration. The different algorithms are illustrated and discussed along with a real case study concerning the UAV flight over the Basilica di Santa Maria di Collemaggio in L'Aquila (Italy). The final result is a rigorous true-orthophoto used to inspect the roof of the Basilica, which was seriously damaged by the earthquake in 2009.

Terrestrial laser scanning is increasingly used in architecture and building engineering for as-built modelling of large and medium size civil structures. However, raw point clouds derived from laser scanning survey are generally not directly ready for generation of such models. A manual modelling phase has to be undertaken to edit and complete 3D models, which may cover indoor or outdoor environments. This paper presents an automated procedure to turn raw point clouds into semantically-enriched models of building interiors. The developed method mainly copes with a geometric complexity typical of indoor scenes with prevalence of planar surfaces, such as walls, floors and ceilings. A characteristic aspect of indoor modelling is the large amount of clutter and occlusion that may characterize any point clouds. For this reason the developed reconstruction pipeline was designed to recover and complete missing parts in a plausible way. The accuracy of the presented method was evaluated against traditional manual modelling and showed comparable results.

The HBIM of the Basilica di Collemaggio in L'Aquila is part of the restoration project of the building seriously damaged by the earthquake in 2009. The project "Ripartire da Collemaggio", funded by ENIservizi, involves an interdisciplinary group called to work together toward a common goal: the need of security of the structures and the need of conservation of the architectonic value of the Basilica. Starting from the photogrammetric and laser scanning survey, interpretation and modelling were needed to create a detailed HBIM to manage the phases of analysis, simulation of structural behavior, economic evaluation of the project, and final restoration. This paper described the generation of the HBIM and its use in the on-going restoration project with a particular attention to the procedures used to preserve the complexity given by photogrammetric and laser scanning data.

Importance of ancient and historical maps is nowadays recognized in many applications (e.g., urban planning, landscape valorisation and preservation, land changes identification, etc.). In the last years a great effort has been done by different institutions, such as Geographical Institutes, Public Administrations, and collaborative communities, for digitizing and publishing online collections of historical maps. In spite of this variety and availability of data, information overload makes difficult their discovery and management: without knowing the specific repository where the data are stored, it is difficult to find the information required. In addition, problems of interconnection between different data sources and their restricted interoperability may arise. This paper describe a new brokering based gateway developed to assure interoperability between data, in particular georeferenced historical maps and geographic data, gathered from different data providers, with various features and referring to different historical periods. The developed approach is exemplified by a new application named GeoPAN Atl@s that is aimed at linking in Northern Italy area land changes with risk analysis (local seismicity amplification and flooding risk) by using multi-temporal data sources and historic maps.

This essay describes an integrated approach – field survey, historic research, climate data, and topography – for the analysis of a complex stratigraphical archaeological site, highlighting its peculiar aspects and its conservation state, and contributing to the studies of this area. The case study is San Calocero monastery in Albenga, one of the most important historical evidence of the city, located on the San Martino Hillside, dating back to the VI century but with a complex historical stratigraphy until the XVI century, along with other relevant archaeological sites, such as the Baptistery, the Ponte Lungo, the churches of San Clemente and San Vittore, which, as long as San Calocero, went through several changes over the years.

Landscapes are dynamic entities, stretching and transforming across space and time, and need to be safeguarded as living places for the future, with interaction of human, social and economic dimensions. To have a comprehensive landscape evaluation several open data are needed, each one characterized by its own protocol, service interface, limiting or impeding this way interoperability and their integration. Indeed, nowadays the development of websites targeted to landscape assessment and touristic purposes requires many resources in terms of time, cost and IT skills to be implemented at different scales. For this reason these applications are limited to few cases mainly focusing on worldwide known touristic sites. The capability to spread the development of web-based multimedia virtual museum based on geospatial data relies for the future being on the possibility to discover the needed geo-spatial data through a single point of access in an homogenous way. In this paper the proposed innovative approach may facilitate the access to open data in a homogeneous way by means of specific components (the brokers) performing interoperability actions required to interconnect heterogeneous data sources. In the specific case study here analysed it has been implemented an interface to migrate a geo-swat chart based on local and regional geographic information into an user friendly Google Earth©-based infrastructure, integrating ancient cadastres and modern cartography, accessible by professionals and tourists via web and also via portable devices like tables and smartphones. The general aim of this work on the case study on the Lake of Como (Tremezzina municipality), is to boost the integration of assessment methodologies with digital geo-based technologies of map correlation for the multimedia ecomuseum system accessible via web. The developed WebGIS system integrates multi-scale and multi-temporal maps with different information (cultural, historical, landscape levels) represented by thematic icons allowing to transfer the richness of the landscape value to both tourists and professionals.

This paper describes a procedure for the generation of a detailed HBIM which is then turned into a model for mobile apps based on augmented and virtual reality. Starting from laser point clouds, photogrammetric data and additional information, a geometric reconstruction with a high level of detail can be carried out by considering the basic requirements of BIM projects (parametric modelling, object relations, attributes). The work aims at demonstrating that a complex HBIM can be managed in portable devices to extract useful information not only for expert operators, but also towards a wider user community interested in cultural tourism.

Automatic identification of high-level repeated structures in 3D point clouds of building façades is crucial for applications like digitalization and building modelling. Indeed, in many architectural styles building façades are governed by arrangements of objects into repeated patterns. In particular, façades are generally designed as the repetition of some few basic objects organized into interlaced and\\or concatenated grid structures. Starting from this key observation, this paper presents an algorithm for Repeated Structure Detection (RSD) in 3D point clouds of building façades. The presented methodology consists of three main phases. First, in the point cloud segmentation stage (i) the building façade is decomposed into planar patches which are classified by means of some weak prior knowledge of urban buildings formulated in a classification tree. Secondly (ii), in the element clustering phase detected patches are grouped together by means of a similarity function and pairwise transformations between patches are computed. Eventually (iii), in the structure regularity estimation step the parameters of repeated grid patterns are calculated by using a Least- Squares optimization. Workability of the presented approach is tested using some real data from urban scenes.

The paper presents an automated procedure for surface reconstruction from digital images. This method was developed for closerange photogrammetric applications, with a particular attention to terrestrial free-form objects that can be modelled with point clouds extracted from images. Therefore, the paper is not directly concerned with architectural elements, where objects feature breaklines and discontinuities that are preferably modelled with manual measurements. The implemented algorithm (MGCM+) integrates two image matching techniques developed in Photogrammetry and Computer Vision in order to obtain metric results in an automated way. Different strategies were exploited to successfully combine both strategies, along with several new improvements. Starting from a set of images and their orientation parameters a preliminary seed model is extracted by using a patch-based algorithm (PMVS). Then, a multi-photo refinement via LSM (MGCM) improves the precision of results and provides a statistical evaluation through a variance-covariance matrix.